How I Described My Time Machine to People of the Middle Ages

"The 2036 Spacetime Continuer"
"'Greased Hawking'"
"A time machine"
"One of those present to past dealies"
"Not magic"
"Difficult to explain"
"Magic"
"Black"
"Whichever the good one is"
"White?"
"Arrow-resistant"
"Flame retardant"
"In the opposite direction of a serf denouncing taxation"
"In the opposite direction of a serf denouncing taxation that you have to stare really hard at for an extended amount of time without looking away, even for just a second, to be able to see"
"Catapult intolerant"